"""
# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""

from collections import OrderedDict

from paddle import nn


class ClassInstantier(OrderedDict):
    """Instantiates layers lazily when accessed."""

    def __getitem__(self, key):
        content = super().__getitem__(key)
        cls, kwargs = content if isinstance(content, tuple) else (content, {})
        return cls(**kwargs)


ACT2CLS = {
    "gelu_tanh": (nn.GELU, {"approximate": "tanh"}),
}
ACT2FN = ClassInstantier(ACT2CLS)


def get_activation_fn(hidden_act: str):
    if hidden_act == "gelu_pytorch_tanh":
        return ACT2FN["gelu_tanh"]
    raise KeyError(f"function {hidden_act} not found in ACT2FN mapping {list(ACT2FN.keys())}")
